UVA 10313 Pay the Price

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　　算法：用前缀和把O(n^3)的dp优化成O(n^2)。注意：（1）long long。（2）L1、L2不一定在[1,300]内。（3）没有空行（不用处理空行能过）。

//10313 Pay the Price Accepted C++ 0.056 2012-11-20 11:23:14#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int MAXN = 300+5;const int MAX = 300;int N, L1, L2;long long d[MAXN][MAXN], f[MAXN][MAXN];char line[100];int main(){d[0][0] = f[0][0] = 1;for (int i = 1; i <= MAX; i++)for (int j = 1; j <= i; j++){d[i][j] = f[i-j][min(j, i-j)];f[i][j] = f[i][j-1]+d[i][j];}while (gets(line)){int n = sscanf(line, "%d%d%d", &N, &L1, &L2);if (n > 0){if (n == 1)printf("%lld\n", f[N][N]);else if (n == 2)printf("%lld\n", f[N][min(L1, N)]);else if (L1 > N)printf("0\n");else if (L1 > 0)printf("%lld\n", f[N][min(L2, N)]-f[N][L1-1]);elseprintf("%lld\n", f[N][min(L2, N)]);}}return 0;}