本文共 1450 字，大约阅读时间需要 4 分钟。

??????n????S?????????????????????????a_i?b_i???????????????????????????

????

????

#include 
   
    #include 
    
     #include 
     
      using namespace std;int main() {    int n, S;    cin >> n >> S;    vector
      
        a(n), b(n);    for (int i = 0; i < n; ++i) {        cin >> a[i] >> b[i];    }    vector
       
         dp(S + 1, 0);    dp[0] = 1;    for (int i = 0; i < n; ++i) {        int min_sum = 0, max_sum = 0;        for (int j = 0; j <= S; ++j) {            if (dp[j] > 0) {                min_sum = min(min_sum, j + a[i]);                max_sum = max(max_sum, j + b[i]);            }        }        if (max_sum > S) max_sum = S;        if (min_sum > S) {            dp = vector
        
         (S + 1, 0); break; } for (int j = max(0, S - max_sum); j <= S; ++j) { int current = j; for (int k = a[i]; k <= b[i]; ++k) { if (current - k >= 0 && dp[current - k] > 0) { dp[current] += dp[current - k]; } } } } cout << dp[S] << endl; return 0;}
        
       
      
     
    
   

????

???????????????????????????????????????????

转载地址：http://vdgf.baihongyu.com/