Question

有关用C++求一个数列的最大子序列和，运行始终存在问题，实在找不到问题所在，求助各位

#include <iostream>

#include <vector>
usingnamespacestd;
int max(int a,int b,int c){
if (a>=b) {
if (a>=c)
return a;
else
if (b>=c)
return b;
else
return c;
}
else
if (b>=c)
return b;
else
return c;
}
int maxSumRec(constvector<int> & a,longint left,longint right){
if (left==right)
return a[left];

int center=(left+right)/2;
int maxLeftSum=maxSumRec(a, left, center);
int maxRightSum=maxSumRec(a, center+1, right);

int maxLeftBorderSum=a[center],leftBorderSum=0;
for (int i=center; i>=left; i--) {
leftBorderSum+=a[i];
if (leftBorderSum>maxLeftSum) {
maxLeftBorderSum=leftBorderSum;
}
}

int maxRightBorderSum=a[center+1],rightBorderSum=0;
for (int j=center+1; j<=right; j++) {
rightBorderSum+=a[j];
if (rightBorderSum>maxRightBorderSum) {
maxRightBorderSum=rightBorderSum;
}
}

int maxMiddleSum=maxLeftBorderSum+maxRightBorderSum;

returnmax(maxLeftSum, maxRightSum, maxMiddleSum);
}
int main(){
vector<int> a;
char next_char;
int next_num;
cout<<"Please enter a list:\n";
cin.get(next_char);
while (next_char!='\n') {
if (!(isdigit(next_char)||next_char=='-')) {
next_char=cin.get();
continue;
}
cin.putback(next_char);
cin>>next_num;
a.push_back(next_num);
next_char=cin.get();
}
cout<<"You entered:\n";
for (int k=0; k<a.size(); k++) {
cout<<a[k]<<" ";
}
cout<<endl;

longint size=a.size();
cout<<"The max sonsum is:\n";
cout<<maxSumRec(a, 0, size-1);

return0;
}

Answer 1

int maxSub(const vector<int> &a){
int max = 0;
int sum = 0;
for(int i=0; i<a.size(); i++){
sum += a[i];
if(sum > max){
max = sum;
}
else if (sum < 0){
sum = 0;
}
}
return max;
}

把vector直接丢到这个function里面就可以了

Answer 2

leftBorderSum>maxLeftSum 改为 leftBorderSum>maxLeftBorderSum

追问

谢谢，昨天发完问题再看一遍就发现了，打到问题补充里面竟然百度不显示，我那编译系统会根据已打的几个字母来自动从前面代码找寻有相同顺序字母的变量或函数等，昨天那里岩画选错了。。。