c++之前缀和及差分

参考例题洛谷p1083

#include 
#include 
using namespace std;

const int maxn = 1e6 + 10;
int r[maxn] = {0};
int b[maxn] = {0};
int d[maxn] = {0};
int s[maxn] = {0};
int t[maxn] = {0};
int c[maxn] = {0};
int k;
int main()
{
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
    {
        cin >> r[i];
    }
    for (int i = 1; i <= m; i++)
    {
        cin >> d[i] >> s[i] >> t[i];
    }
    int low = 1;
    int high = n;
    while (low < high)
    {
        memset(b, 0, sizeof(b));
        memset(c, 0, sizeof(c));
        int mid = (low + high) / 2;
        for (int i = 1; i <= mid; i++)
        {
            b[s[i]] += d[i];
            b[t[i] + 1] -= d[i];
        }
        int add = 0;
        for (k = 1; k <= n; k++)
        {
            add += b[k];
            c[k] += add;
            if (c[k] > r[k])
                break;
        }
        if (k <= n)
            high = mid;
        else
            low = mid + 1;
    }
    if (high == n)
    {
        cout << 0;
        return 0;
    }
    else
    {
        cout << -1 << endl;
        cout << high;
    }
    return 0;
}

写的超级棒的博客