求数组最大的连续和

如果求连续的乘积和就要考虑负数相乘和0的情况……！

连续乘积子序列最大

 

mi[1] = mx[1] = a[1];
        for(int i = 2;i <= n;i++){
            mi[i] = min(min(a[i],a[i]*mi[i-1]),a[i]*mx[i-1]);
            mx[i] = max(max(a[i],a[i] * mi[i-1]),a[i] * mx[i-1]);
        }

 

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <cstdlib>
#include <stack>
#include <cctype>
#include <string>
#include <malloc.h>
#include <queue>
#include <map>

using namespace std;

const int INF = 0xffffff;
const double esp = 10e-8;
const double Pi = 4 * atan(1.0);
const int Maxn = 2000+10;
const long long mod =  2147483647;
const int dr[] = {1,0,-1,0,-1,1,-1,1};
const int dc[] = {0,1,0,-1,1,-1,-1,1};
typedef long long LL;

LL gac(LL a,LL b){
    return b?gac(b,a%b):a;
}

int a[10000];

int maxsum(int x,int y){ ///算法复杂nln(n)，f(n) = 2 * f(n/2)+n,f(1) = 1;
    if(y-x == 1)
        return a[x];
    int m = x + (y-x)/2;
    int mm = max(maxsum(x,m),maxsum(m,y));
    int L = a[m-1];
    int R = a[y-1];
    int v = 0;
    for(int i = m-1;i > -1;i--){
        v += a[i];
        L = max(v,L);
    }
    v = 0;
    for(int i = m;i < y;i++){
        v += a[i];
        R = max(R,v);
    }
    return max(mm,L+R);
}

int main()
{
#ifndef ONLINE_JUDGE
    freopen("inpt.txt","r",stdin);
#endif
    int n;
    while(~scanf("%d",&n)){
        int s[10000];
        memset(s,0,sizeof(s));
        int mx = -0xfffff;
        int tt = -1;
        for(int i = 1;i <= n;i++){
            scanf("%d",&a[i]);
            s[i] += (s[i-1] + a[i]);
            if(s[i] >= mx){
                mx = s[i];
                tt = i;
            }
        }
        int mi = a[1];
        if(tt != -1){
            for(int i = 2;i < tt;i++){  ///在已经找到的最大和的前面寻找最小值
                mi = min(mi,[i]);
            }
        }
        cout << "D1:" << mx - mi << endl;
        int xx = maxsum(1,n+1);
        cout << "D2:"<< xx << endl;
    }
    return 0;
}