给定一整数序列A1,A2,…,An(可能有负数),求A1到An的一个自序列,使得Ai到Aj的和最大。例如:整数序列-2,11,-4,13,-5,2,-5,-3,12,-9的最大子序列为21(从A2到A9)
最差的方法
```
var@H_403_9@ a = [-2@H_403_9@,11@H_403_9@,-4@H_403_9@,13@H_403_9@,-5@H_403_9@,2@H_403_9@,-3@H_403_9@,12@H_403_9@,-9@H_403_9@]
var@H_403_9@ b = new@H_403_9@ Set()
for@H_403_9@(let n in@H_403_9@ a){
let nm = [];
for@H_403_9@(let m = n;m<a.length;m++){
nm.push(a[m])
}
add(...nm)
}
function@H_403_9@ add@H_403_9@(...nums@H_403_9@)@H_403_9@{@H_403_9@
nums.reduce((x,y)=>{
b.add(x+y);
return@H_403_9@ x+y;
})
}
Math.max(...b)
优化
`@H_403_9@`` var@H_403_9@ a = [-2@H_403_9@,-9@H_403_9@] var@H_403_9@ b = new@H_403_9@ Set() for@H_403_9@(let@H_403_9@ n in@H_403_9@ a){ a.reduce((x,y)=>{ b.add(x+y); return@H_403_9@ x+y; }) a.shift() } Math@H_403_9@.max(...b)@H_403_9@
ES6
```
var@H_403_9@ a = [-2@H_403_9@,-9@H_403_9@]
var@H_403_9@ b = new@H_403_9@ Set()
new@H_403_9@ class@H_403_9@ res@H_403_9@{@H_403_9@
constructor(){
a.reduce((x,y)=>{
b.add(x+y);
return@H_403_9@ x+y;
})
a.shift()
if@H_403_9@(a.length) new@H_403_9@ res()
}
}
Math.max(...b)
最优-动态规划
var@H_403_9@ a = [-2@H_403_9@,-9@H_403_9@]
function@H_403_9@ method@H_403_9@(data)@H_403_9@{ var max = 0; var m = data.length; var sum = 0; for(var i=0;i<m;i++){ sum+=data[i]; if(sum>max){ max=sum; }@H_403_9@else@H_403_9@ if@H_403_9@(sum<0)@H_403_9@{ sum = 0; }@H_403_9@ } return@H_403_9@ max@H_403_9@;@H_403_9@
}
method@H_403_9@(a)@H_403_9@@H_403_9@