数字三角形问题 算法入门经典

递归方法：

#include <stdio.h>#define maxn 100int buf[maxn][maxn];int n;int d(int i, int j){int t1, t2;return i == n ? buf[i][j] : buf[i][j] + (((t1 = d(i+1, j)) > (t2 = d(i+1, j+1))) ? t1 : t2);}int main(){       /*5912 1510 6 82 18 9 519 7 10 4 16        结果 59*/int i, j;scanf("%d", &n);for(i = 1; i <=n; ++i)for(j = 1; j <= i; ++j)scanf("%d", &buf[i][j]);printf("%d\n", d(1, 1));return 0;}

记忆搜索（递归）：

#include <stdio.h>#include <string.h>#define maxn 100int buf[maxn][maxn];int d[maxn][maxn];int n;int dfunc(int i, int j){if(d[i][j] >= 0)  return d[i][j];return d[i][j] = buf[i][j] + (i == n ? 0  : dfunc(i+1, j) >  dfunc(i+1, j+1) ? dfunc(i+1, j) : dfunc(i+1, j+1));}int main(){int i, j;scanf("%d", &n);for(i = 1; i <= n; ++i)  for(j = 1; j <= i; ++j)  scanf("%d", &buf[i][j]);    memset(d, -1, sizeof(d));printf("%d\n", dfunc(1, 1));return 0;}

递推方法：

#include <stdio.h>#define maxn 200int d[maxn][maxn];int n;void dfunc(){int i, j;for(i = n - 1; i >= 1; --i)for(j = 1; j <= i; ++j)   d[i][j] += d[i+1][j] > d[i+1][j+1] ? d[i+1][j]:d[i+1][j+1];} int main(){int i, j; scanf("%d", &n);for(i = 1; i <= n; ++i)for(j = 1; j <= i; ++j)  scanf("%d", &d[i][j]);dfunc();printf("%d\n", d[1][1]);return 0;}