POJ 3040 Allowance(贪心经典题目）

• Source Code

  #include<iostream>#include<algorithm>#include<string.h>using namespace std;struct node{int x, y;}cow[21];bool cmp(node a, node b){return a.x < b.x;}int main(){int N, C;while (cin >> N >> C){int sum = 0, used[21];memset(used, 0, sizeof(used));int i, j;for (i = 0, j = 0; i < N; i++){int a, b; cin >> a >> b;if (a >= C) sum = sum + b;else {cow[j].x = a;cow[j++].y = b;}}sort(cow, cow + j, cmp);while (1){int s = C,temp=0;for (i = j - 1; i >= 0; i--){if (s > 0&&cow[i].y>0){temp = min(cow[i].y, s / cow[i].x);used[i] += temp;s = s - temp*cow[i].x;}}if (s > 0){for (i = 0; i < j; i++){if (used[i] < cow[i].y&&cow[i].x>=s){used[i]++;s = s - cow[i].x; break;}}}if (s > 0) break;sum++;for (i = 0; i < j; i++){cow[i].y -= used[i];used[i] = 0;}}cout << sum << endl;}return 0;}