HDU - 1231 最大连续子序列

Posted 2020-10-02 SomnusMistletoe

题意：给定K个整数的序列{ N1, N2, ..., NK }，其任意连续子序列可表示为{ Ni, Ni+1, ...,Nj }，其中 1 <= i <= j <= K。最大连续子序列是所有连续子序列中元素和最大的一个，例如给定序列{ -2, 11, -4, 13, -5, -2 }，其最大连续子序列为{ 11, -4, 13 }，最大和为20。在今年的数据结构考卷中，要求编写程序得到最大和，现在增加一个要求，即还需要输出该子序列的第一个和最后一个元素。

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<stack>
#include<deque>
#include<queue>
#include<list>
#define lowbit(x) (x & (-x))
const double eps = 1e-8;
inline int dcmp(double a, double b){
    if(fabs(a - b) < eps) return 0;
    return a > b ? 1 : -1;
}
typedef long long LL;
typedef unsigned long long ULL;
const int INT_INF = 0x3f3f3f3f;
const int INT_M_INF = 0x7f7f7f7f;
const LL LL_INF = 0x3f3f3f3f3f3f3f3f;
const LL LL_M_INF = 0x7f7f7f7f7f7f7f7f;
const int dr[] = {0, 0, -1, 1, -1, -1, 1, 1};
const int dc[] = {-1, 1, 0, 0, -1, 1, -1, 1};
const int MOD = 1e9 + 7;
const double pi = acos(-1.0);
const int MAXN = 10000 + 10;
const int MAXT = 10000 + 10;
using namespace std;
int a[MAXN];
int main(){
    int K;
    while(scanf("%d", &K) == 1){
        if(K == 0) return 0;
        for(int i = 0; i < K; ++i){
            scanf("%d", &a[i]);
        }
        int st, ed, sum, ans, tmpst;
        st = ed = sum = tmpst = 0;
        ans = -1;
        bool ok = false;
        for(int i = 0; i < K; ++i){
            if(sum < 0){
                sum = a[i];
                tmpst = i;
            }
            else{
                sum += a[i];
            }
            if(sum > ans){
                ok = true;
                ans = sum;
                st = tmpst;
                ed = i;
            }
        }
        if(!ok){
            printf("0 %d %d\n", a[0], a[K - 1]);
        }
        else{
            printf("%d %d %d\n", ans, a[st], a[ed]);
        }
    }
    return 0;
}