TYVJ 1097 MM不哭 解题报告

#include <stdio.h>
#include <stdlib.h>
#define min(a, b) ((a)<(b)?(a):(b))
int left[1001][1001], right[1001][1001];
int w[1001][1001];
struct girl{
int d, w;
}girls[1001];
int n;

void srch_r(int a, int b);
void srch_l(int a, int b)
{
if(a - 1 >= 1 && left[a - 1][b] > left[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[a].d - girls[a - 1].d)){
left[a - 1][b] = left[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[a].d - girls[a - 1].d);
srch_l(a - 1, b);
}
if(b + 1 <= n && right[a][b + 1] > left[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[b + 1].d - girls[a].d)){
right[a][b + 1] = left[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[b + 1].d - girls[a].d);
srch_r(a, b + 1);
}
}

void srch_r(int a, int b)
{
if(a - 1 >= 1 && left[a - 1][b] > right[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[b].d - girls[a - 1].d)){
left[a - 1][b] = right[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[b].d - girls[a - 1].d);
srch_l(a - 1, b);
}
if(b + 1 <= n && right[a][b + 1] > right[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[b + 1].d - girls[b].d)){
right[a][b + 1] = right[a][b] + (w[1][a - 1] + w[b + 1]
) * (girls[b + 1].d - girls[b].d);
srch_r(a, b + 1);
}
}

int main(int argc, char **argv)
{
int i, j;
int s;
scanf("%d%d", &n, &s);
for(i = 1; i <= n; i++){
scanf("%d%d", &girls[i].d, &girls[i].w);
}
for(i = 1; i <= n; i++){
for(j = i; j <= n; j++){
right[i][j] = left[i][j] = 0xFFFFFFF;
w[i][j] = w[i][j - 1] + girls[j].w;
}
}
left[s][s] = right[s][s] = 0;
srch_l(s, s);
srch_r(s, s);
printf("%d\n", min(left[1]
, right[1]
));
return 0;
}