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I'm getting WA and I have no idea why. What could be wrong?

#include <cstdio>
#include <cstring>

char a[1010];
char b[1010];
int dyn[1010][1010];

int lcs() {
int ca = strlen(a);
int cb = strlen(b);

for (int i = 0; i < ca; i++) {
for (int j = 0; j < cb; j++) {
int curr = 0;
if (j > 0 ...