2020 Multi-University Training Contest 2 String Distance
题解：
这个官方题解说的很清楚了，比赛的时候没有时间想了，让我想可能也想不到，挺思维的。
#include <bits/stdc++.h>
#define inf 0x3f3f3f3f
using namespace std;
typedef long long ll;
const int maxn = 2e5+10;
int g[maxn][30],f[30][30];
char a[maxn],b[maxn];
int main() {
int t;
scanf("%d", &t);
while (t--) {
scanf("%s%s", a + 1, b + 1);
int n = strlen(a + 1), m = strlen(b + 1);
for (int i = 1; i <= n+10; i++) memset(g[i], inf, sizeof(g[i]));
for (int i = n; i >= 1; i--) {
int x = a[i] - 'a' + 1;
g[i][x] = i;
for (int j = 1; j <= 26; j++) g[i][j] = min(g[i][j], g[i + 1][j]);
}
int q;
scanf("%d", &q);
while (q--) {
int l, r;
scanf("%d%d", &l, &r);
memset(f, inf, sizeof(f));
f[0][0] = l - 1;
for (int i = 1; i <= m; i++) {
int x = b[i] - 'a' + 1;
// printf("i=%d
",i);
for (int j = 0; j <= min(i,r-l+1); j++) {
if (j == 0) f[i][j] = l - 1;
f[i][j] = min(f[i - 1][j], f[i][j]);
if(j>=1&&f[i - 1][j - 1]!=inf) f[i][j]=min(f[i][j],g[f[i - 1][j - 1]+1][x]);
// printf("f[%d][%d]=%d
",i,j,f[i][j]);
}
}
ll ans = r - l + 1 + m;
// printf("ans=%lld
",ans);
for(int j=m;j>=0;j--){
if(f[m][j]<=r){
// printf("j=%d
",j);
ans -= 2*j;
break;
}
}
printf("%lld
",ans);
}
}
return 0;
}
/*
1
qaqaqwqaqaq
qaqwqaq
3
3 9
1 7
2 8
*/