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<!DOCTYPE HTML>
<html lang="zh-CN">
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<meta name="keywords" content="牛牛的回文串（区间dp）, IT学习">
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line(duixiang[i].x,duixiang[i].y,duixiang[j].x,duixiang[j].y,0,i,j)
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line(duixiang[i].x,duixiang[i].y,move.x,move.y,1,i,1)
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<script>
var _createClass = function () {function defineProperties(target, props)
{ for (var i = 0; i < props.length; i++)
{var descriptor = props[i];descriptor.enumerable = descriptor.enumerable || false;descriptor.configurable = true;if ("value" in descriptor)
descriptor.writable = true;Object.defineProperty(target, descriptor.key, descriptor);}}
return function (Constructor, protoProps, staticProps)
{if (protoProps) defineProperties(Constructor.prototype, protoProps);
if (staticProps) defineProperties(Constructor, staticProps);
return Constructor;};}();function _classCallCheck(instance, Constructor)
{if (!(instance instanceof Constructor)) {throw new TypeError("Cannot call a class as a function");}}
var getRandom = function getRandom(min, max) {
return Math.random() * (max - min) + min;
};
var getRandomInt = function getRandomInt(min, max) {
return Math.floor(Math.random() * (max - min)) + min;
};
var getRandomColor = function getRandomColor() {
var colors = [
'rgba(231, 76, 60, 1)', // red
'rgba(241, 196, 15, 1)', // yellow
'rgba(46, 204, 113, 1)', // green
'rgba(52, 152, 219, 1)', // blue
'rgba(155, 89, 182, 1)' // purple
];
return colors[getRandomInt(0, colors.length)];
};
// Particle//粒子模块
var
Particle = function () {
function Particle(system, x, y) {_classCallCheck(this, Particle);
this.system = system;
this.universe = this.system.world.universe;
this.x = x;
this.y = y;
this.color = getRandomColor();
this.life = 1;
this.aging = getRandom(0.990, 0.999); // 0.99, 0.999 || 0.999, 0.9999
this.r = getRandomInt(12, 16);//初始粒子半径范围
this.speed = getRandom(18, 18.5);//粒子爆炸速度范围
this.velocity = [
getRandom(-this.speed, this.speed),
getRandom(-this.speed, this.speed)];
}_createClass(Particle, [{ key: 'update', value: function update(
dt) {
this.life *= this.aging;
if (
this.r < 0.1 ||
this.life === 0 ||
this.x + this.r < 0 ||
this.x - this.r > this.universe.width ||
this.y + this.r < 0 ||
this.y - this.r > this.universe.height)
{
this.system.removeObject(this);
}
this.r *= this.life;
this.x += this.velocity[0];
this.y += this.velocity[1];
} }, { key: 'render', value: function render(
ctx) {
// Main circle //亮圈模块
ctx.fillStyle = this.color;
ctx.beginPath();
ctx.arc(this.x, this.y, this.r*1.2, 0, 2 * Math.PI, false);
ctx.fill();
ctx.closePath();
var r = this.color.match(/([0-9]+)/g)[0];
var g = this.color.match(/([0-9]+)/g)[1];
var b = this.color.match(/([0-9]+)/g)[2];
// Gradient//梯度变化曲线
var spread = 1.5;
var gradient = ctx.createRadialGradient(
this.x, this.y, this.r,
this.x, this.y, this.r * spread);
gradient.addColorStop(0, 'rgba(' + r + ', ' + g + ', ' + b + ', 0.5)');
gradient.addColorStop(1, 'rgba(' + r + ', ' + g + ', ' + b + ', 0)');
ctx.globalCompositeOperation = 'lighter';
ctx.fillStyle = gradient;
ctx.beginPath();
ctx.arc(this.x, this.y, this.r * spread, 0, 2 * Math.PI, false);
ctx.fill();
ctx.closePath();
ctx.globalCompositeOperation = 'source-over';
// Aberration//偏差
var offset = this.r * 0.5;
var color = 'rgba(' + g + ', ' + b + ', ' + r + ', 0.5)';
ctx.globalCompositeOperation = 'lighter';
ctx.fillStyle = color;
ctx.beginPath();
ctx.arc(this.x + offset, this.y + offset, this.r, 0, 2 * Math.PI, false);
ctx.fill();
ctx.closePath();
ctx.globalCompositeOperation = 'source-over';
} }]);return Particle;}();
// Crown //水波纹圈模块
var
Crown = function () {
function Crown(system, x, y) {_classCallCheck(this, Crown);
this.system = system;
this.x = x;
this.y = y;
this.r = getRandomInt(5, 15); // 5, 20 水波纹圈半径范围
this.mod = 1.1;
this.life = 0.5; //水波纹线
this.aging = getRandom(0.830, 0.899);
this.speed = getRandom(8, 9);
this.color = {
r: getRandomInt(236, 242),
g: getRandomInt(70, 80),
b: getRandomInt(50, 70) };
this.angle1 = Math.PI * getRandom(0, 2);
this.angle2 = this.angle1 + Math.PI * getRandom(0.3, 0.4);//水波纹圈完整度
}_createClass(Crown, [{ key: 'update', value: function update(
dt) {
this.life *= this.aging;
if (this.life <= 0.0001) this.system.removeObject(this);
this.r += Math.abs(1 - this.life) * this.speed;
this.x1 = this.x + this.r * Math.cos(this.angle1);
this.y1 = this.y + this.r * Math.sin(this.angle1);
this.angle3 = this.angle1 + (this.angle2 - this.angle1) / 2;
this.x2 = this.x + this.r * this.mod * Math.cos(this.angle3);
this.y2 = this.y + this.r * this.mod * Math.sin(this.angle3);
} }, { key: 'render', value: function render(
ctx) {
var gradient = ctx.createRadialGradient(
this.x, this.y, this.r * 0.9,
this.x, this.y, this.r);
gradient.addColorStop(0, 'rgba(' + this.color.r + ', ' + this.color.g + ', ' + this.color.b + ', ' + this.life + ')');
gradient.addColorStop(1, 'rgba(' + this.color.r + ', ' + this.color.g + ', ' + this.color.b + ', ' + this.life * 0.5 + ')');
ctx.fillStyle = gradient;
ctx.beginPath();
ctx.arc(this.x, this.y, this.r, this.angle1, this.angle2, false);
ctx.quadraticCurveTo(this.x2, this.y2, this.x1, this.y1);
ctx.fill();
ctx.closePath();
} }]);return Crown;}();
// Explosion //爆炸模块
var
Explosion = function () {
function Explosion(world, x, y) {_classCallCheck(this, Explosion);
this.world = world;
this.x = x;
this.y = y;
this.objects = [];
var particles = getRandomInt(10, 30); // 10, 30 amount of particles//爆炸 粒子数量
var crowns = particles * getRandom(0.4, 0.5);
while (crowns-- > 0) {this.addCrown();}
while (particles-- > 0) {this.addParticle();}
}_createClass(Explosion, [{ key: 'update', value: function update(
dt) {
this.objects.forEach(function (obj) {
if (obj) obj.update(dt);
});
if (this.objects.length <= 0) {
this.world.clearExplosion(this);
}
} }, { key: 'render', value: function render(
ctx) {
this.objects.forEach(function (obj) {
if (obj) obj.render(ctx);
});
} }, { key: 'addCrown', value: function addCrown()
{
this.objects.push(new Crown(this, this.x, this.y));
} }, { key: 'addParticle', value: function addParticle()
{
this.objects.push(new Particle(this, this.x, this.y));
} }, { key: 'removeObject', value: function removeObject(
obj) {
var index = this.objects.indexOf(obj);
if (index !== -1) {
this.objects.splice(index, 1);
}
} }]);return Explosion;}();
// World
var
ConfettiWorld = function () {function ConfettiWorld()
{_classCallCheck(this, ConfettiWorld);}_createClass(ConfettiWorld, [{ key: 'init', value: function init()
{
this.objects = [];
window.addEventListener('click', this.explode.bind(this));
// Initial explosion //初始爆炸
var counter = 0;
while (counter-- > 0) {
this.explode({
clientX: window.event.clientX, //getRandomInt(10, this.universe.width) , //this.universe.width / 2,
clientY: window.event.clientY //getRandomInt(10, 50) //this.universe.height / 2
});
}
} }, { key: 'update', value: function update(
dt) {
this.objects.forEach(function (obj) {
if (obj) obj.update(dt);
});
var amount = this.objects.reduce(function (sum, explosion) {
return sum += explosion.objects.length;
}, 0);
} }, { key: 'render', value: function render(
ctx) {
this.objects.forEach(function (obj) {
if (obj) obj.render(ctx);
});
} }, { key: 'explode', value: function explode(
event) {
var x = event.clientX;
var y = event.clientY;
this.objects.push(new Explosion(this, x, y));
} }, { key: 'clearExplosion', value: function clearExplosion(
explosion) {
var index = this.objects.indexOf(explosion);
if (index !== -1) {
this.objects.splice(index, 1);
}
} }]);return ConfettiWorld;}();
// Time
var
Time = function () {
function Time() {_classCallCheck(this, Time);
this.now = 0; // current tick time
this.prev = 0; // prev tick time
this.elapsed = 0; // elapsed time from last tick
this.delta = 0; // time from last update
this.fps = 60; // desired fps
this.step = 1 / 60; // step duration
}_createClass(Time, [{ key: 'update', value: function update(
time) {
this.now = time;
this.elapsed = (this.now - this.prev) / 1000;
this.prev = this.now;
this.delta += this.elapsed;
} }, { key: 'raf', value: function raf(
func) {
window.requestAnimationFrame(func);
} }, { key: 'hasFrames', value: function hasFrames()
{
return this.delta >= this.step;
} }, { key: 'processFrame', value: function processFrame()
{
this.delta -= this.step;
} }]);return Time;}();
// Canvas
var
Universe = function () {
function Universe(element) {_classCallCheck(this, Universe);
this.el = element;
this.ctx = this.el.getContext('2d');
this.pixelRatio = window.devicePixelRatio;
this.time = new Time();
this.worlds = {};
this.world = null; // current state
this.updateSize();
window.addEventListener('resize', this.updateSize.bind(this));
this.addWorld('confetti', ConfettiWorld);
this.setWorld('confetti');
this.start();
}_createClass(Universe, [{ key: 'start', value: function start()
{
this.time.raf(this.tick.bind(this));
} }, { key: 'tick', value: function tick(
time) {
this.time.update(time);
if (this.time.hasFrames()) {
this.update();
this.time.processFrame();
}
this.render();
this.time.raf(this.tick.bind(this));
} }, { key: 'update', value: function update()
{
this.world.update(this.time.step);
} }, { key: 'render', value: function render()
{
var gradient = this.ctx.createLinearGradient(0, 0, this.width, this.height);
// gradient.addColorStop(0, '#34495e');
//gradient.addColorStop(1, '#2c3e50');
this.ctx.clearRect(0, 0, this.width, this.height);
// this.ctx.fillStyle = '#2c3e50'
// //this.ctx.fillStyle = gradient;
// // this.ctx.fillRect(0, 0, this.width, this.height);
this.world.render(this.ctx);
}
// Helpers 库
}, { key: 'updateSize', value: function updateSize()
{
this.width = window.innerWidth;
this.height = window.innerHeight;
this.el.width = this.width * this.pixelRatio;
this.el.height = this.height * this.pixelRatio;
this.el.style.width = window.innerWidth + 'px';
this.el.style.height = window.innerHeight + 'px';
this.ctx.scale(this.pixelRatio, this.pixelRatio);
} }, { key: 'addWorld', value: function addWorld(
worldName, World) {
this.worlds[worldName] = new World();
this.worlds[worldName].universe = this;
this.worlds[worldName].init();
} }, { key: 'setWorld', value: function setWorld(
worldName) {
this.world = this.worlds[worldName];
} }]);return Universe;}();
// Main
console.clear();
var element = document.querySelector('#canvas1');
window.Canvas= new Universe(element);</script>
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牛牛的回文串（区间dp）
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<span id="page__date">2019-05-23</sapn>
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<p></p><p> </p> <blockquote> <h2>题目描述</h2> <p>牛牛喜欢回文串，牛妹给了牛牛一个字符串S，牛牛想把S变成回文串<br> 牛牛可以做如下三种操作<br> 1：在任意位置增加一个字符<br> 2：删除一个字符<br> 3：改变一个字符<br><br> 每种操作都有限定的字符，比如，只能删除’a’,增加’b’,把’c’变成’d’等等<br> 每种操作都有相应的代价<br> 用M条语句来描述能进行的操作<br> add c x 表示增加c字符需要x的代价<br> erase c x表示删除c字符需要x的代价<br> change c1 c2 x表示将c1 改成c2需要x的代价<br> 求牛牛想要得到回文串需要的最少代价<br> 如果不行输出-1</p> <h2>输入描述:</h2> <pre>第一行输入一个字符串S(都是小写字母)表示牛妹给牛牛的串(1 ≤ |S| ≤ 50)<br>第二行输入一个整数m (0 ≤ m ≤ 50)<br>接下来m行的格式是<br>add c x<br>erase c x<br>change c1 c2 x<br>三种中的一种<br>c c1 c2都是小写字母<br>1 ≤ x ≤ 100000<br>所有允许的操作去除x部分后都是不同的</pre> <h2>输出描述:</h2> <pre>输出一个整数</pre> <p>示例1</p> <h2>输入</h2> <pre>racecar<br>0</pre> <h2>输出</h2> <pre>0</pre> <p>示例2</p> <h2>输入</h2> <pre>caaaaaab<br>change b a 100000<br>change c a 100000<br>change c d 50000<br>change b e 50000<br>erase d 50000<br>erase e 49999</pre> <h2>输出</h2> <pre>199999</pre> <p>示例3</p> <h2>输入</h2> <pre>moon<br>erase o 5<br>add u 7<br>change d p 3<br>change m s 12<br>change n d 6<br>change s l 1</pre> <h2>输出</h2> <pre>-1</pre> <p>示例4</p> <h2>输入</h2> <pre>xab<br>change a c 1<br>change b d 1<br>change c e 1<br>change d e 1<br>add y 1<br>change y z 1<br>change x z 1</pre> <h2>输出</h2> <pre>7<br></pre> </blockquote> <p> </p> <p>AC代码：</p> <div class="has"><p></p>